Gas turbines, for example inter alia under the type designation GT13E2, are operated with an annular combustion chamber. The combustion itself takes place preferably, but not exclusively, via premixing burners (referred to in the following text for short as burners), such as those disclosed in EP-A1-321 809 or EP-A1-704 657, with these documents and the further development of these premixing burners derived therefrom being an integrating component of this application. By way of example, an annular combustion chamber such as this is disclosed in DE-A1-196 44 378, a detail of which is reproduced in FIG. 1 of this application. The gas turbine 10 illustrated in FIG. 1 has a turbine housing 11 which, in the area of the combustion chamber 15, surrounds a plenum chamber 14 which is filled with compressed combustion air. The annular combustion chamber 15 is arranged concentrically around the central rotor 12 in the plenum chamber 14, and merges into a hot-gas channel 22. The area is bounded on the inside by an inner shell 21′, and on the outside by an outer shell 21. The inner shell 21′ and the outer shell 21 are each separated on a separating plane into an upper part and a lower part. The upper part and the lower part of the inner and outer shell 21′, 21 are connected on the separating plane such that an annular area is formed which guides the hot gas produced by the burners 16 to the rotor blades 13 of the turbine. The separating plane is required for assembly and disassembly of the machine. The combustion chamber 15 itself is clad with special wall segments 17.
In the described embodiment, the inner and outer shell 21′, 21 are cooled by convection. In this case, cooling air which enters the plenum chamber 14, arriving as a compressor air flow 23 from the compressor, flows predominantly in the opposite flow direction to the hot gas in the hot-gas channel 22. This cooling air then flows from the plenum chamber 14 on through a respective outer and inner cooling channel 20 and 20′, which cooling channels are formed by cooling shirts 19, 19′ which surround the shells 21, 21′ at a distance. The cooling air flows along the shells 21, 21′ in the cooling channels 20, 20′ in the direction of the combustion chamber shroud 18, which surrounds the combustion chamber 15. There, the air is then available as combustion air to the burners 16.
The hot gas flows from the burners 16 to the turbine (stator blades 13) and in the process flows along the surfaces on the hot-gas side of the inner and outer shells 21′ 21. The flow along these surfaces is, however, not homogeneous in this case, but is influenced by the arrangement of the burners 16.
The inner and outer shells 21′, 21 are subject to both thermal and mechanical loads. In conjunction with the method of operation as well, these loads govern the life of the inner and outer shells 21′, 21 and the inspection intervals which result from this. The non-uniformities in the flow as mentioned above occur both on the hot-gas side and on the cooling-air side. The non-uniformities on the hot-gas side result primarily from the burner arrangement. The non-uniformities on the cooling-air side are caused predominantly by fittings in the cooling channels 20, 20′.